Re: BUG #3965: UNIQUE constraint fails on long column values - Mailing list pgsql-bugs

"Heikki Linnakangas" <heikki@enterprisedb.com> writes:

"Heikki Linnakangas" <heikki@enterprisedb.com> writes:

> Gregory Stark wrote:
>> "Heikki Linnakangas" <heikki@enterprisedb.com> writes:
>>
>>> As others have pointed out, CREATE UNIQUE INDEX i ON ((md5(column)) is a pretty
>>> good work-around.
>>
>> Unless you need cryptographic security I would not suggest using MD5. MD5 is
>> intentionally designed to take a substantial amount of CPU resources to
>> calculate.
>
> Return type of hash* functions is just 32 bits. I wonder if that's wide enough
> to avoid accidental collisions? Depends on the application of course...

Oh, I missed that you were suggesting a UNIQUE index. That seems unsafe to me
even for md5 or its ilk. But that would depend on the application too.

--
  Gregory Stark
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